Equidistant cylindrical projection is known as an image format for a panoramic image in which a whole sky scene as viewed from an observation point is projected onto a two-dimensional plane. According to this projection, an omniazimuth scene that spans 360 degrees horizontally and spans 180 degrees vertically is included in a rectangular shape of image data which has an aspect ratio of 1:2. By using such a panoramic image, it is possible to realize a panorama viewer for displaying a scene in any desired direction depending on how the user manipulates the direction of its viewpoint, for example.